Apparatus for deep drawing metal with hydraulically controlled dies



`July Filed Jpne 7; 1965 F. MVWILLIAMSON APPARATUS FOR DEEP DRAWINGMETAL WITH HYDRAULICALLY CONTROLLED DIES ATTORNEYS July 8, 1969 F. M.WILLIAMSON 3,453,848 APPARATUS FOR DEEP DRAWING METAL WITH 4HYDRAULICALLY CONTROLLED DIES Filed June v, 1965 sneetof s /ATTORNEYJuly 8, 1969 y F. M. wlLLlAMsoN 3,453,843 APPARATUS FOR DEEP DRAWINGMETAL WITH HYDRAULICALLY CONTROLLED DIES Filed June 7. 1963 sheet 3 of 3BIO Flag-5 FIG,.6

l INVENTOR.

ATTORNEYS United States Patent O 3,453,848 APPARATUS FOR DEEP DRAWINGMETAL WITH HYDRAULICALLY CONTROLLED DIES Floyd M. Williamson, Detroit,Mich., assignor to Di-Dro Engineering Company, Detroit, Mich., acorporation f Michigan Filed June 7, 1965, Ser. No. 461,935 Int. Cl.B21b 37/06;B21d 22/20 U.S. Cl. 72-28 16 Claims ABSTRACT OF THEDISCLOSURE Die structure for deep drawing metal parts including a rstdie part having an opening extending therethrough with steppedprogressively smaller diameters proceeding away from the second die partand a second die part ini cluding a plurality of concentric telescopeddie punches adapted to proceed through the opening in the rst die partin progressive forming phases with one of the die punches remainingstationary at each step in the first die part and pressure pads engagedwith each of said die punches and die control structure operablyassociated with each of said pressure pads for preventing movement ofthe particular die punch engaged by the pad with respect to the otherdie punches before a predetermined pressure is applied thereto and forproviding a continually varying pressure on the pressure pad duringforming of a workpiece and the method of deep drawing metal workpiecesaccomplished by the structure.

The invention relates to forming metal articles by a press operation andrefers more specifically to a process of and structure for deceleratingor gradually decreasing the draw pad pressure applied by work holdingpressure pads in die structure during single stroke deep drawing ofmetal workpieces with novel hydraulic die control and die structure.

In the past drawing of long hollow, metal vessels, such as shells,tanks, bathtubs, baskets and the like has been diicult or impossible dueto limitations in known drawing processes and die structures. Thus, indeep drawing process of the past the draw pad pressure holding aworkpiece has usually not been decelerated as the workpiece is formed tocompensate for the increased ditliculty of forming the work as itconforms to a die and `die punch. In fact, with past structure whereindraw pad pressure has been applied through springs, the force holdingthe workpiece normally tends to increase as the resistance to drawingincreases.

Also, with past die structure deep drawing has often been accomplishedin separate steps. The separate drawing steps are progressively moredifficult due to work hardening and setting of the metal between theseparate steps.

In addition prior processes of and structure for deep drawing aworkpiece have not always been suitable for use with both hydraulic andcrank presses. Prior deep drawing operations have also been somewhatrestricted by space limitations resulting from the general requirementfor a relatively long press ram construction supporting a relativelylong die punch considered necessary to accomplish the drawing operation.

It is therefore one of the purposes of the present invention yto providean improved process for deep drawing a metal workpiece.

Another object is to provide a process for deep drawing a metalworkpiece including gradually decreasing or decelerating the draw padpressure restraining the workpiece ice during forming of the workpieceas resistance to the drawing of the workpiece increases.

Another object is to provide a process for deep drawing a metalworkpiece as set forth above wherein the workpiece is continuouslyformed in multiple phases.

Another object is to provide improved structure for deep drawing a metalworkpiece. Another object is to provide structure for deep drawing ametal workpiece including means for applying draw pad pressure to theworkpiece during forming thereof, and means for gradually decreasing ordecelerating the draw pad pressure on the workpiece during forming ofthe workpiece as resistance to the drawing of the workprece increases.

Another object is to provide structure as set forth above and furtherincluding means for preloading the pressure applying means before theworkpiece is drawn.

Another object is to provide structure as set forth above wherein thestructure for deep drawing a metal workpiece further includes a diehaving telescopic punch structure for continuously forming the workpiecein multiple phases.

Another object is to provide a die including telescopic die punches forcontinuously forming a workpiece in multiple phases.

Another object is to provide hydraulic die control apparatus fordecelerating or gradually decreasing draw pad pressure applied to aworkpiece drawn in drawing die structure on a press or the like as thepress is cycled.

Another object is to provide a process of and structure for deep drawinga workpiece which is simple, economical and efficient.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, illustrating a preferred embodiment of theinvention. wherein:

FIGURE 1 is a diagrammatic longitudinal section view of telescoping diestructure and hydraulic control apparatus therefor mounted on ahydraulic press and constructed in accordance with the invention forperforming the process of the invention shown with the die structure andpress and in an open position.

FIGURE 2 is a diagrammatic longitudinal section view of modifiedtelescoping die structure, press and hydraulic control apparatus similarto that illustrated in FIGURE 1 with the modied die structure and pressin a closed position.

FIGURE 3 is a detailed diagrammatic representation, partly in section ofhydraulic die control apparatus suitable for use in conjunction with thedie structures and presses illustrated in FIGURES 1, 2, 5 and 6.

FIGURE 4 is a detailed diagrammatic representation, partly in section ofa modification of a portion of the die control apparatus illustrated inFIGURE 3.

FIGURE 5 is a diagrammatic longitudinal section view of die structureand hydraulic control apparatus therefor mounted on a crank press andconstructed in accordance with the invention for performing the processof the invention shown with the die structure and press in a partlyclosed position.

FIGURE 6 is a diagrammatic longitudinal section view of the diestructure, press and hydraulic control apparatus therefor illustrated inFIGURE 5 showing the die structure and press in a substantially fullyclosed position.

With particular reference to the figures of the drawings, one embodimentof the present invention will now be disclosed in detail.

As illustrated in FIGURE l the telescoping die structure 10 is securedto a hydraulic press 12. Only the bed 14 and the rain 16 of thehydraulic press 12 are shown. Hydraulic die control apparatus 18 forcontrolling draw pad pressure in the die structure 18 in each ofmultiple phases of operation thereof is secured to the telescopingupper, punch part 20 of the die structure 10.

In operation a workpiece 24, initially in the form of a ilat metalblank, which it is desired to form into a long cylindrical hollow vesselclosed at one end, as illustrated in FIGURE 2, is placed on thestationary lower, die part 26 of the die structure 10 and the punch part20 of the die structure is moved toward the die part 26. The workpiece24 is continuously drawn in multiple phases through the die members 52,54 and 56 as it passes through openings 28, 30 and 32 in the die part26. The drawing of the workpiece 24 is accomplished by the concentrictelescoping hollow die punches 34 and 36 and the Solid center die punch38 of the punch part 20 of die structure 10 as the punch part 20 ismoved toward the die part 26.

The hydraulic die control apparatus 18 provides gradually decreasing ordecelerating draw pad pressures on the workpiece 24 during each of themultiple phases of a drawing operation of the die structure 10 tocompensate for the increasing resistance to drawing of the workpieceduring the drawing process.

More specically the lower, die part 26 of the die structure 10illustrated in FIGURE 1 includes the individual die blocks 40, 42 and 44having the concentric centrally located openings 28, 30 and 32 thereinof progressively smaller circular cross section. The openings 28, 30 and32 are uniform in diameter throughout the length of each separateopening. The die blocks 40, 42 and 44 are further provided with circularrecesses 46, 48 and 50 respectively therein concentric with the openings28, 30 and 32 respectively in which the hardened annular die members 52,54 and 56 respectively are positioned.

As shown in FIGURE 2, the die block 42 may be supported by convenientmeans, such as spacing blocks 64 or the like, on and in spaced relationto die block 44 to permit removal, transversely of the die structure 10,of material trimmed from the workpiece 24 by the die member 56 inconjunction with die punch 38. The trimming of material from theworkpiece 24 by die punch 38 and die member 56 during drawing of theworkpiece 24 will be considered in detail subsequently.

The upper, punch part of the die structure 10 includes the mountingmember 66 secured in a fixed position on the lower end of the ram 16 ofthe press 12 by convenient means (not shown) and the mounting member 68rigidly secured in spaced relation to the mounting member 66 by means ofrods 70 only one of which is shown which are positioned in spacedrelation around the periphery of members 66 and 68 and are secured tothe members 66 and 68 by convenient means, such as bolts 72 and 74 atthe opposite ends thereof.

A hydraulic cushion 86 including cylinder 80 and piston 84 is secured tothe mounting member 66 by convenient means (not shown). The interior ofthe cylinder 80 is hydraulically connected t0 the die control valve 58of the hydraulic control apparatus 18 through passage 82 in mountingmember 66. Piston 84 is engaged with block 90 connected to piston sleeve88 and is positioned for vertical movement into and out of the cylinder80. The hydraulic cushion 86 provides draw pad pressure for the thirdand iinal phase of forming of workpiece 24 through block 90, the end ofsleeve 88, rods 124, punch supporting member 130 and die punch 36, aswill be considered subsequently.

The sleeve 88 is further connected at the upper end to the annularhydraulic cushion supporting member 96 which is guided for verticalmovement by the rods 70 extending through the angularly spaced apartperipheral openings 98 in member 96. Hydraulic cushions 94 are supportedin angularly spaced relation about the periphery of member 96. Eachcushion 94 includes a cylinder '100 connected to the die control valve60 of the hydraulic 4l control apparatus 18 through the hydraulic fluidconduit 182. A piston 104 is positioned within each of the cylinders forvertical movement into and out of the respective cylinders.

An annular pressure pad 108 is sleeved over sleeve 88 for verticalmovement with respect thereto. The pad 108 is also guided by the shafts70 extending through angularly spaced openings 110 around the peripherythereof. Pressure pad 108 applies pressure to pistons 104 when thecushion supporting member 96 and pad 108 are moved toward each other. Aswill be seen subsequently, cushions 94 supply the draw pad pressurethrough pressure pad 108, rods 112, cushion and punch supporting memberand die punch 34 for the second phase of drawing of the workpiece.

The rods 112 extend in angularly spaced relation vertically throughperipheral openings 114 in mounting member 68 and similar openings 116in the punch supporting member 118. The rods 112 are in engagement atthe top with the pressure pad 1108. The punch and hydraulic cushionsupporting member 120 to which the outer hollow cylindrical die punch 34and hydraulic cushion 122 are secured is in engagement with the bottomsof rods 112.

Rods 124 pass through the angularly spaced apart peripheral openings 126and 128 in the mounting member 68 and punch supporting member 118respectively and are in engagement with the block 90 and bottom ofsleeve 88. The punch supporting member 130 is engaged with the lowerends of the rods 124 and supports the inner hollow cylindrical die punch36 Which is rigidly secured thereto.

The punch supporting member 118 to which the center solid cylindricaldie punch 38 is rigidly secured is in turn secured to the die mountingmember 68 by convenient means (not shown).

Hydraulic cushions '122 each including a cylinder 134 and piston 138 arecarried peripherally in angularly spaced relation by the member 120 andare connected by means of a hydraulic fluid conduit 136 to the diecontrol valve 62 of the hydraulic control apparatus 18. The pistons 138are positioned within the cylinders 134 for vertical movement into andout of the cylinders. The cushions 122 apply draw pad pressure to theworkpiece 24 through pressure pad 148 during the first phase of drawingof workpiece 24 as will be seen subsequently.

Guide posts, stops and the like may be provided in conjunction with thepressure pad 148, cushion and punch supporting member 120 and punchsupporting member 130 and in conjunction with the other members of thedie structure where desired. Such die structure is well known and `formsno part of the present invention and will therefore not be considered indetail herein.

As indicated above the die punch 38 is reciprocally mountedconcentrically lwith and within the hollow die punch 36 and extendsthrough the opening 142 in punch supporting member 130, while the diepunch 36 eX- tends through the hollow cylindrical die punch 34 andthrough the concentric opening 144 of the cushion and punch supportingmember 120i. The die punch 34 extends through the opening 146 in thepressure pad 148 on which pistons 138 bear.

The die control values 58, 60 and 62 are the same and are similarlysupplied with hydraulic fluid from tank 150 through flexible hydraulicuid line 152. Return of the hydraulic fluid to the tank 150 is alsoaccomplished through hydraulic lluid line 152 in conjunction withcontrol valves 58, 60 and 62. The hydraulic fluid in tank 158 ismaintained at a predetermined pressure with air supplied to the tank 150through pressure regulating valve 168 from air supply conduit 170.

Since the die control valves 58, 60 and 62 are all the same only diecontrol valve 62 will be considered in detail. The die control valve 62includes the check valve 172 positioned between the tank 150 and thehydraulic cushions 122 and a parallel positioned pressure relief valvei174 illustrated best in FIGURE 3. Y

|Check valve 172 includes the valve member 180 and spring 182 held inpassage 184 in valve block 186 by plug 188. The valve member 180.permits flow of hydraulic fluid through conduit 152 to conduit 102 andinto cylinders 134 but prevents reverse hydraulic liuid ow through theconduit I152.

The pressure relief valve 174 includes a valve member 190 urged toward aclosed position by spring I192, the tension on which is adjustable bymeans of the adjusting screw 194 acting on plug 196 in valve passage 198in valve block 158. When the pressure in the cylinders 134 exceeds apredetermined value set by the adjustment of the adjusting screw 194,the valve member 190 is caused to move up, as shown in FIGURE 3, topermit draining of hydraulic fluid from the cylinders 134 through thepassage 160 back to the tank 150.

The dies control valves 58, 60 and 62 permit operation of the diestructure in multiple phases to be considered in detail subsequently.With only the die control valves 58, 60 and 62 the pressure applied tothe workpiece by cushions F86, 94 and 122 in each phase of operation ofthe die structure 410 may be dilerent but the pressure on the workpiecein each phase of operation will be the same during the phase ofoperation as determined by the setting of the pressure relief valve.

In the modified die structure illustrated in FIGURE 2 wherein the samereference numerals are used to` designate the same elements as in FIGURE1, only the upper die control valve 58 is used. The cushions 94 and 122are supplied with hydraulic liuid through valve 58 and the flexiblefluid supply line 248 connecting with passage 82 in junction block 270.With the structure of FIGURE 2 the different pressures on Ithe workpiecein the different phases of operation of the die structure will bedetermined by the different total cross-sectional area of the cushionpistons associated with the phase of opera-tion, as will be consideredsubsequently.

With only the die control valves 58, 60 and 62 the pressure initiallyapplied to the workpiece is limited by the pressure applied to thehydraulic yfluid in the tank 150. Also, deceleration or controlleddecreasing of the pressure applied to the workpiece during the phases ofoperation is not possible with only the die control valves 58, 60 and62. Therefore, any of the die control valves S8, 60 or 62 or all of themmay be further provided with an intensifier unit and/or a deceleratingvalve, such Vas the intensifier unit 176 and decelerating valve 178,illustrated in FIGURE 3 in conjunction with die control valve 62.

The intensier unit 176 includes a small diameter cylinder 200 incommunication vat the upper end with passage 202 in valve block 186through passage 204 therein. The small diameter cylinder 200 is also incommunication at the lower end thereof with the upper end of the largediameter cylinder 212. The lower end of lthe cylinder 212 is incommunication with the decelerating valve structure 178 through theconduit 216. A small diameter pist'cm 218 is positioned in the smalldiameter cylinder 200 and is rigidly connected with the large diameterpiston 220 by the rigid shaft 224. Thus, on application of a relativelysmall force per unit area in the lower portion of the cylinder 212, arelatively large force per unit area will be provided in the upper endof the small diameter cylinder 200.

The decelerating valve 178 includes a valve block 226 having a passage228 therein connected with the conduit 216 from the intensifier 176 yatone end and extending at right angles to and connected at the other endto the passage 230 in the valve block 226. One end of passage 230 isclosed by a plug 232 as shown in FIGURE 3. An adjustable limiting valve234 is secured in the valve block 226 between the intersecting otherends of passages 228 Iand 230.

An offset passage 236 is provided in the block 226 having the portion238 at one end in communication with the passage 228 and extendingsubstantially parallel to the passage 230 which portion 238 is closed bythe plug 240 in the valve block 226. The passage 236 further includesthe portion 242 extending substantially parallel to the passage 228 andin communication with the portion 238. A bleeder valve 244 for timing ofthe escape of air from the lower portion of cylinder 212 is providedbetween the portions 238 and 242 of passage 236.

The passage 236 further includes the portion 246 again extendingsubstantially parallel to the passage 230 and offset from the portion238 of the passage 236 and which is open at the end, as illustrated inFIGURE 3 to provide for escape of air under pressure from intensifier176 when it is desired to decelerate the pressure in the cushions 122.If the pressure in the cushions 122 is to be accelerated -a source ofair under pressure is connected -to portion 246 of passage 236.

A further passage 250 extends through the valve block 226 substantiallyperpendicular to and intersecting both the passages 230 and 236, asshown in FIGURE I3. A two-way valve 252 is provided at the intersectionof the passage 250 and the portion 246 of passage 236. Valve 252 isoperated by the mechanical linkage 254and may be biased by spring 256into the position shown in FIGURE 3 wherein the passage 250 is incommunication with the passage 230 and passage 236 is closed. Rotationof valve 252 ninety degrees will open passage 236 and close passage 250.Actuation of the mechanical linkage 254 to rotated valve 252 may be by amechanical connection to the ram 16 of press 12 on lowering of ram 16.Alternatively of course electrical actua-ting means for the mechanicallinkage 254 may be provided actuated on closing of a limit switch or thelike by ram 16 of press 12. The passage 250 in die block 226 isconnected through conduit 258 to a pressure regulating valve 260 and anon-ofi valve 262 connected to a source of air under pressure, such asconduit 170 through conduit 264.

The over-al1 operation of the die structure 10 will be consideredassuming that all of the die control valves 58, 60 `and 62 are providedas in FIGURE 1 and each are operably associated with an intensier unit176 and a decelerating valve, as in FIGURE 3. With the die structure 10initially in the position illustrated in FIGURE 1,

the cylinders 80, and 134 will be filled with hydraulic Huid from thetank through check valves 172 in the respective die control valves 58,`60 and 62. The valve 252 of the decelerating valve 178 of the diecontrol valves will bein the position shown in FIGURE 3 and the valve262 will be open whereby air under pressure from conduit 264 is suppliedthrough the pressure regulating valve 2-60 through the conduit 258,passage .250, passage 230 and passage 228 past the partially openadjustable valve 234 and into the lower end of cylinder 212. Thepressure will be multiplied through the intensifier unit 176 wherebyhydraulic fluid at a substantial pressure will .be applied to thepistons 84, 104 and 138 to initially hold the pads 108 and 148 and sleve88 together with block 90 iu an extended position, as shown in FIGURE l.

The pressure is initially maintained at predetermined fixed values inthe cylinders 80, 100 and 134 due to the setting of the pressure reliefvalves 174. If necessary to maintain an initial pressure against lossesif hydraulic a preload cylinder and piston may be employed inconjunction with any or all of the cushions 86, 94 and 122 as will beconsidered in more detail subsequently along with the die structure ofFIGURE-S 5 and 6.

As the ram 16 of press 12 descends the draw pad 148 initially contactsthe workpiece 24 to provide pressure on the workpiece in conjunctionwith the lower die part 2'6. Continued descent of ram 16 changes theposition of the valve 252 in the decelerating valve 178 associated withdie control valve 62 to open the portion 246 of the 7 conduit 236. Thus,as the die punch members 34, 36 and 38 acting as a unit begin to drawthe workpiece 24 through the die member 52 and the opening 28 in the dieblock 40, the pressure applied to the cylinders 134 and thus to theworkpiece 24 through pistons 138 begins to decelerate or decrease as thepressure in the lower end of cylinder 212 bleeds out through openpassage 236 past bleed valve 244.

On continued movement of the rarn 16 in a downward direction the diepunches 34, 36 and 38 acting as a unit pass through the opening 146 inpad 148 through die member 52 and into opening 28 through die block 40.Pad 148 eventually abuts against the cushion and punch supporting member120 with the pistons 138 forced into the cylinders 134. The workpiece 24in the rst phase of the continuous draw is thus drawn through die member52 into the opening 28 with the edges thereof held by the pressure pad148 with a decelerating pressure controlled by the setting of the bleedvalve 244 of the decelerating valve structure 178 associated with thedie control valve 62.

Further downward movement of the punch supporting member 120 is at thistime prevented by the lower end of the hollow punch 34 which will nowpress the bottom of the now cup-shaped workpiece 24 against the top ofthe annular die member S4 in die block 42 with au initial draw padpressure determined -by the setting of the pressure relief valveassociated with the die control valve `60.

Continued downward movement of the ram 16 of press 12 will cause thecushion and punch supporting member 130 to move toward the punchsupporting member 120. Movement of the member 130 toward the member 120on downward movement of ram 16 is resisted by cushions 94 acting throughpressure pad 108 and rods 112. During movement of the member 130 towardmember 120, the hollow cylindrical punch 36 will pass out of the lowerend of the hollow cylindrical punch 34 along with the solid die punch 38acting as a unit therewith into the opening 30 in the die block 42through die member 54 to form the workpiece 24 in the second of thecontinuons drawing phases.

The pressure pad 108 again initially offers large resistance to relativemovement of the members 120 and 130 toward each other which isdetermined by the setting of the pressure relief valve in the diecontrol valve 60 associated therewith, as indicated above. As the ramcontinues its downward movement the pressure in the hydraulic cushions94 is gradually decelerated or decreased as the resistance to drawingthe workpiece 24 through die member 54 into the opening 30 in die block42 increases as 'before due to actuation of a mechanical linkage, suchas linkage 254 on a decelerating valve associated with the die controlvalve 94.

When the ram 16 has moved down to the point where the punch supportingmember 120 is almost in contact with the cushion and die supportingmember 130, the pistons 104 are almost completely inserted in thecylinders 100. The lower end of the die punch 36 will at this time reston the bottom of the cup-shaped workpiece irnmediately above the top ofthe die member 56 to apply drawing pad pressure on the workpieceinitially determined 'by the setting of the pressure relief valve in thedie `control valve 58 during the third and final phase of the continuousforming of workpiece 24.

Continued movement downward of the ram 16 of press 12 will producecontinued downward movement of the center, solid, die punch 38. The rods124 at this time will urge the sleeve 88, block 90 and piston 84 movabletherewith into the cylinder 80 again against a decelerating pressureapplied to the cylinder 80 from the decelerating valve'associated withthe die control valve S8.

The die 10 at the end of the downward stroke of the press ram 16 will bein a position as indicated in FIG- URE 2 with the workpiece 24 formedinto a deep drawn cylinder closed at the lower end.

Approximately fty percent of the draw is performed through the rst diemember '52 with twenty-live percent of the draw being through each ofthe die members 54 and 56. The difference in the draw through the diemembers 52, 54 and 56 is due to the greater diiculty in drawing themetal workpiece 24 after it has been drawn in the first phase throughthe die member S2.

It will be understood that in the operation considered above that any orall of the die control valves '58, 60 and 462 may be provided without anintensifier unit 176 and without a decelerating valve 178. However,wrinkles, tears and the like in workpiece 24 are more completelyeliminated due to the gradually relieved pressure holding the workpieceperipherally in each of the successive phases of the draw whendecelerating valves 178 are provided.

As illustrated in FIGURE 2 the lower die member 42 may, if desired, beraised above the die member 44 and positioned on spacing blocks 64 topermit removal of the portion of the workpiece 24 which is trimmed fromthe workpiece 24 between the shoulder 266 formed on the lower end of thedie punch 38 in conjunction with the annular die member 56. The upperend of the workpiece 24 will be pinched between the die member 56 andthe shoulder 266 on die punch 38 as the punch 38 passes through the diemember to trim the finished workpiece 24 to a predetermined length. Thetrimmed portion of the workpiece may be removed through the space 268.

The decelerating valve structure 272 illustrated in FIG- URE 4 is amodification of the decelerating valve structure 178 illustrated inFIG'ULRE 3. The Valve structure 272 dilfers from the valve structure 178in that the air under pressure is supplied through a passage 274 fromregulating valve 276 on opening of the valve 278 and is supplied to thelower portion of the intensifier unit 176 through conduit 280 frompassage 282. A valve 284 is provided between the passages 274 `and 282.The air pressure is exhausted through the offset passage 286 having theportions 288, 290 and 292 and including the bleed valve 294 thereinpositioned as shown in FIGURE 4. The valve 296 is positioned in thepassage 286 to open and close the passage 286 on actuation of themechanical linkage 298.

In operation of the valve structure illustrated in FIG- URE 4 the airunder pressure is again bled out of the intensifier unit 176 through theconduit 280 and passage 286 in response to downward movement of thepress to actuate the linkage 298 and open the passage 286 to atmospherethrough the valve 296. Again the release of the air pressure in theintensifier and the consequent deceleration of pressure in the hydrauliccushions is controlled by the setting of the valve 294.

The hydraulic die control structure illustrated in FIG- URE 3, is notonly suitable for use in conjunction with the telescoping die structure10, as illustrated in FIGUR-ES 1 and 2, with hydraulic press 12 but isalso suitable for use in conjunction with other die structures and presstypes, such as the die structure 300 and the crank preSS 302 illustratedin FIGURES 5 and `6. The die structure 300 illustrated in FIGURES 5 and6 is useful in deep drawing larticles having inwardly inclined sides,such as for example, a bathtub.

As shown in FIGURES 5 and 6 the crank press 302 includes the bed 304,the rotating crank wheel 306 and the mechanical link 308 pivoted at theopposite ends 310 and 312 to the crank wheel 306 of the press 302 andthe upper forming die supporting member 314 of the die structure 300,respectively. The press structure 302 also includes the cam member 316which has la mechanical connection 318 to the crank wheel 306 so as tobe synchronized in rotation therewith. The cam 316 forces the binder 320of the press structure 302 downward to place the hydraulic cushions 322carried by the binder 320 into contact with the die structure pressurepad 324 for a predetermined time during a cycle of the press 302.

The die structure 300 includes the bottom forming die 326 having acavity 328, including the tapered sides 330 rigidly secured to the bed304 of the crank press 302. The bottom die member 326 includes themounting flanges 332 and flanges 334 for supporting a workpiece 336 inposition for forming and for supporting the preload cylinder 338 of thehydraulic control apparatus generally indicated 340.

The die structure 300 further includes the die supporting member 314,previously indicated connected to the crank wheel 306 of the crank press302 by mechanical link 308 for vertical reciprocation thereby. The upperforming die 342 is connected to the die supporting member 314 byconvenient means, such las bolts (not shown).

An .actuating member 344 is secured to the die supporting member 314 forvertical movement therewith into and out of the slot 346 cut therefor inthe binder 320 for moving the preload piston 348 in the preload cylinder338 during downward movement of the upper forming die 342.

The hydraulic control apparatus 340 for the die structure 300 includesthe preload cylinder and piston noted above, a plurality of hydrauliccushions 322 including pistons 352 and cylinders 354 connected to a diecontrol valve 358 including a pressure relief valve 360 and a checkvalve 362 and an intersifier unit 364 and pressure decelerating valve366 connected to the die control valve 35S as before. A tank forsupplying hydraulic fluid under air pressure, as illustrated in FIGURE3, and pressurized lair supply means will be provided in conjunctionwith the hydraulic control apparatus 340 connected as illustrated inFIGURE 3.

Thus, in operation of the die structure illustrated in FIGURES and 6,with the crank wheel 306 of the press 302 in a position to fully retractthe upper forming die 342, the cam 316 is in a position with respect tothe binder 320 to permit the binder to assume a position wherein thepressure pad 324 is allowed to move away from the lower forming die. Theworkpiece blank 336 is positioned on the top of the lower forming die326 and the crank wheel 306y is rotated to start the upper forming die342 down.

The actuating member 344 then contacts the preload piston 348 to drivehydraulic fluid from the preload cylinder 33S and provide apredetermined pressure in the hydraulic cushions 322 carried by binder320 set by the pressure relief valve 360 in the die control valve 358.The cam 316 then forces the binder 320 down so that the pistons 352engage the pressure pad 324 and forces it into contact with the outerperiphery of the workpiece 336 to provide an initial drawing pressureholding the workpiece 336 between the pressure pad 324 and the upperflange 334 of the lower forming die 326.

The binder 320 is maintained in this position by the cam 316 during theremainder of the downward stroke of the press structure 302. During theremainder of the downward stroke of the press 302 the upper forming die342 forms the workpiece 336 in conjunction with the lower forming die326. The pressure applied to the pressure pad 324 during forming ofworkpiece 336 is again decelerated to prevent wrinkling and tearing ofthe workpiece 336 through action of the decelerating Valve 366 in thedie control valve 358 due to actuation of the decelerating valve by thepress structure 302 in its downward movement.

On the subsequent upward stroke of the press structure 302 the preloadcylinder 338 is again filled with hydraulic fluid from hydraulic fluidline 356 to extend the piston 348, as shown in FIGURE 5. The position ofthe press 302 and die 300 at the finish of the forming stroke isillustrated in FIGURE 6.

While one embodiment of the present invention and modifications thereofhave been disclosed in detail, it will be understood that otherembodiments and modifications are contemplated. It is the intention toinclude all embodiments and modifications of the invention as aredefined by the appended claims within the scope of the invention.

What I claim as my invention is:

1. In combination a press, die structure including first and second dieparts secured to the press for forming a metal workpiece positionedtherebetween on relative movement of the die parts toward each other onactuation of the press and at least one pressure pad and hydraulic diecontrol apparatus connected to the die structure for providing a varyingpressure on the workpiece through the pressure pad during forming of theworkpiece, said hydraulic die control apparatus including a source ofhydraulic fluid under pressure, at least one hydraulic cushion operablyassociated with the pressure pad for applying hydraulic pressure to thepad, check valve structure between the source of hydraulic fluid andhydraulic cushion for applying hydraulic fluid to the cushion at apressure substantially equal to the pressure from the source ofhydraulic fluid, a pressure relief valve positioned between the sourceof hydraulic fluid and the hydraulic cushion for returning hydraulicfluid from the cushion to the supply of hydraulic fluid at a Selectedcushion fluid pressure, an intensifier connected to the hydrauliccushion for increasing the pressure of the hydraulic fluid therein and adecelerating valve connected to a source of air under pressure and theintensifier for activating the intensifier to increase the pressure ofthe hydraulic fluid in the cushions and for decelerating the pressure inresponse to movement of the press structure.

2. Structure as set forth in claim 1 wherein the decelerating valvecomprises a valve block, a first passage eX- tending through said valveblock, one end of which is plugged and the other end of which isconnected to the intensifier, an adjustable metering valve in said firstpassage, a second passage in said valve block in communication with thefirst passage between the end thereof connected to the intensifier andthe metering valve closed at on end adjacent the connection to the firstpassage and open at the other end, a third passage in said valve blockin communication with both the first and second passages, a two-wayvalve operable between the second and third passages for alternativelyopening the other end of said second passage and closing the thirdpassage and for `opening said third passage and closing said other endof said second passage in response to movement of the press, and a bleedvalve positioned in the second passage between the connection betweenthe first and second passages and the two-way valve.

3. Structure as set forth in claim 1 wherein the decelerating valvecomprises a valve block, a first passage eX- tending through said valveblock connected at one end to the intensifier, a metering valve in thefirst passage, a second passage extending through said valve blockclosed at one end and open to the atmosphere at the other end, saidsecond passage communicating with said first passage adjacent the closedend of the second passage, a valve in the second passage adjacent theopen end thereof and means connected to the valve for opening the secondpassage on downward movement of the press and a bleed valve in thesecond passage positioned between the intersection between the first andsecond passages and the valve in the second passage.

4. Structure as set forth in claim 2 wherein the second die part has anopening extending therethrough with stepped progressively smallerdiameters proceeding away from the first die part and the first die partincludes a plurality of concentric telescoped die punches adapted toproceed downwardly through the opening in the lower die part inprogressive forming phases with one of the die punches remainingstationary at each smaller diameter in the second die part and pressurepads operably associated with each of said die punches and die controlstructure for preventing movement of the die punches with respect toeach other before a predetermined pressure is applied therebetween.

5. Structure as set forth in claim 4 wherein separate die controlstructure is provided in conjunction with each separate pressure pad.

6. Structure as set forth in claim 4 wherein a single die controlstructure is provided for control of all of the separate pressure pads.

7. Structure as set forth in claim 4 wherein the center die punch of thetelescoped punches is provided with a reduced diameter outer endcooperable with the smallest diameter of the second die portion fortrimming the edges of a iinished workpiece drawn through the second dieportion.

8. In combination with a crank press including a crank wheel and a pressbed and means synchronized with said crank wheel, die structureincluding a bottom forming die member secured on the bed of the presshaving a die cavity therein, a pressure pad positioned directly abovethe bottom die member, a binder positioned directly above the pressurepad for engagement by said synchronized means during a predeterminedportion of the cycle of the press for moving the binder toward thepressure pad into a predetermined position with respect thereto, aplurality of hydraulic cushions supported by the binder adapted to exerta decelerating hydraulic pressure on the pressure pad with the binder inthe predetermined position, a'n upper forming die member, a diesupporting member secured to the upper forming die member and meanssecuring the die supporting member to the crank wheel of the press formoving the upper forming die member vertically into and out of thecavity in the lower forming die member.

9. Structure as set forth in claim 8 and further including a preloadingcylinder operably associated with the die supporting member forsupplying hydraulic pressure to the hydraulic cushions on downwardmovement of the die supporting member before the hydraulic cushionsengage the pressure pad on movement of the binder toward the pressurepad.

10. A decelerating valve comprising a valve block, a irst passageextending through said valve block, one end of which is plugged and theother end of which is open, an adjustable metering valve in said firstpassage, a second passage in said valve block in communication with theirst passage between the outlet end thereof and the metering valvetherein closed at one end adjacent the connection to the rst passage andopen at the other end, a third passage in said valve block incommunication with both the irst and second passages, a two-way valveoperable between the second and third passages for alternatively openingthe other end of said second passage and closing the third passage andfor opening said third passage and closing said other end of said secondpassage in response to a condition external of the valve, and a bleedvalve positioned in the second passage between the connection betweenthe rst and second passages and the two-way valve.

11. A decelerating valve comprising a valve block, a rst passageextending through said valve block open at both ends, a metering valvein the first passage, a second passage extending through said blockclosed at one end and open at the other end, said second passagecornmunicating with said lirst passage adjacent the closed end thereof,a valve in the second passage adjacent the open end thereof and meansconnected to the valve for opening the second passage in response to acondition external of the valve and a bleed valve in the second passagepositioned between the intersection between the first and secondpassages and the valve in the second passage.

12. In combination a press, die structure including first and second dieparts secured to the press for forming a metal workpiece positionedtherebetween on relative movement of the die parts toward each other onactuation of the press and at least one pressure pad and hydraulic diecontrol apparatus connected to the die structure for providing agradually varying pressure on the workpiece through the pressure padthroughout the formation of the workpiece, said hydraulic die controlapparatus including a source of hydraulic fluid under pressure, at leastone hydraulic cushion operably associated with the pressure pad forapplying hydraulic pressure to the pad, check valve structure betweenthe source of hydraulic liuid and hydraulic cushion for applyinghydraulic fluid to the cushion at a pressure substantially equal to thepressure from the source of hydraulic fluid, a pressure relief valvepositioned between the source of hydraulic iiuid and hydraulic cushionfor returning hydraulic fluid from the cushion to the supply ofhydraulic iiuid at a selected cushion uid pressure and means connectedto the hydraulic cushion for gradually decelerating the pressure in thecushion in response to movement of the press structure.

13. Die structure including a first die part having an opening extendingtherethrough with stepped progressively smaller diameters proceedingaway from a second die part and a second die part including a pluralityof concentric telescoped die punches adapted to proceed through theopening in the iirst die part in progressive forming phases with one ofthe die punches remaining stationary at each step in the irst die partand pressure pads engaged with each of said die punches, hydrauliccushion structure and die control structure operably associated witheach of said pressure pads for preventing movement of the particular diepunch engaged by the pad with respect to the other die punches before apredetermined pressure is applied thereto, intensier means connected tothe hydraulic cushions for increasing the pressure therein anddecelerating valve means connected to the intensifier means foractivating the intensifier means to increase the pressure of thehydraulic uid in the cushions and for decelerating the pressure inresponse to movement of the press structure.

14. Structure as set forth in claim 13 wherein a separate die controlstructure is provided `for control of each separate pressure pad.

15. Structure as set forth in claim 13 wherein a single die controlstructure is provided for control of all of the separate pressure pads.

16. Structure as set forth in claim 13 wherein the center die punch ofthe telescoped punches is provided with a reduced diameter outer endcooperable with the smallest diameter of the first die part for trimmingthe edges of a nished workpiece drawn through the first die part.

References Cited UNITED STATES PATENTS 961,131 6/1910 Higgins 72-3492,192,778 3/1940 Stacy 72--351 2,318,819 5/1943 VerSOn 72--349 2,485,35410/ 1949 Brennan '72-352 2,989,019 6/1961 Van Sciver 72-351 3,085,5304/1963 Williamson 72-351 1,550,626 8/1925 Ferris 72--351 RICHARD J.HERBST, Primary Examiner.

U.S. Cl. X.R. 72-349, 351

